1. Field of the Invention
This invention relates generally to a tool for repairing valve elements, and particularly to a tool useful for repairing valve elements in pressurized systems.
2. Description of the Prior Art
It is desirable to have the ability to repair valve elements in pressurized systems, and particularly to remove and replace or service the threadably mounted valve core in pressurized refrigeration systems or the like, without depressurizing the system by removing or losing the refrigerant gas. The pressures most often encountered in such systems vary from 75 lbs./sq. in. to 250 lbs./sq. in. The valve cores and thread sizes etc. are standardized, making it possible to attach a standard tool to the valve fitting, through which the valve core can be passed, after which the passage through the tool is closed. A good sealing mechanism is crucial to maintain pressure when the core is removed, and the need to open an access way to the core complicates matters. Such needs, together with the substantial operating pressures make it necessary to provide a device of great precision as well as very sturdy construction. The tools which have been heretofore known for this purpose have been of relatively complicated construction, making them prone to leak, and/or less dependable and thus expensive to manufacture than necessary.
Fritch, U.S. Pat. No. 3,561,090, discloses a valve core changing tool with a carousel arrangement of relatively rotatable elements with eccentric around the bolt, which is parallel to the valve system. In one rotatable position the old valve core can be removed through an eccentric passageway in the aligned elements with a tool, and in another carousel position the new valve core can be installed.
Olson, U.S. Pat. No. 3,840,967, discloses a tool for servicing a pressurized refrigeration system or the like. Structure is provided to sealably engage the refrigeration system at the valve stem. The valve core is removed with an internally carried tool that is manipulated from the outside but kept in a sealed area to prevent gas leakage. A cutoff valve in the tool seals the pressurized system from the area such that the valve core can then be removed and serviced or, by reversing the procedure, replaced.
Anderson, U.S. Pat. No. 4,305,193, discloses a tool for servicing valves in pressurized systems which provides a pulling device carried in a bore through a block, rotatably mounted in a housing. In one block position, the bore in the block aligns with the valve to allow access and removal of the core therefrom. By rotation the block around an axis perpendicular to the valve stem to a position in which the bore and valve are axially misaligned, the valve is sealed from the bore such that the valve core can be removed from the bore by the block and serviced or replaced. The block is spherical or cylindrical and is sealably captive in the housing. The block and housing must fit tightly around the round contour of the block to prevent gas leakage.
The present invention provides a tool for servicing or replacing valve elements in pressurized systems which can be relatively easily and inexpensively manufactured yet is of a very sturdy construction. The tool can withstand the extreme pressures which can be encountered in refrigeration systems and the like by virtue of a slidable dovetail interlocking system between tool components. The dovetail prevents any loosening that would occur with eccentric-passage bolt-connected elements as in Fritch. The dovetail also improves the seal without need for precisely-matched round parts as in the block and housing of Anderson. The tool of the invention therefore combines effectiveness, durability, safety and economy.